Fuse



Oct 3, 1939. H. A. TRIPLETT ET AL FUSE Filed April 21, 1937 WWW Patented Oct. 3, 1 939 UNITED STATES PATENT OFFICE FUSE Application April 21, 1937, Serial No. 138,188

38 Claims.

This invention relates, generally, to fuse devices and it has particular relation to the construction and assembly of renewable fuse links for universal use which may be inserted in practically any of the fuse housings of the expulsion type that are now being sold.

The object of this invention, generally stated, is to provide a universal fuse link construction that shall be simple and eflicient in operation and which may be readily and economically manufactured and installed.

An important object of this invention is to secure electrical and mechanical contact engagement between the terminals of a fuse link and the strain and fusible elements and the flexible conductor forming parts of the same.

Another important object of this invention is to provide for securing a terminal, of a fusible element of a fuse link for example, to a stranded conductor or flexible lead in such manner as to provide a high degree of permanent electrical contact engagement therebetween.

Another object of this invention is to interconnect a tubular terminal and a flexible conductor formed of a plurality of strands of .wire in such manner that the maximum outside dimension of the assembly will be substantially the same as the initial outside diameter of the terminal and not substantially greater than the diameter of an unclamped portion of the flexible conductor.

A specific'object of this invention is to provide high contact pressure between a tubular metal sleeve or socket and a flexible conductor comprising a plurality of strands of wire by deforming a substantial portion of the sleeve or socket onto the strands of the conductor in such mannenthat the high contact pressure remains after the means employed to producethe same is removed.

Another object of this invention is to secure a fusible element and a strain element in a terminal in a new and improved manner.

Another important object of this invention is to provide for securing a strain element and a fusible element to the inside-sand outside, respectively, of the tubular end portions of a pair of fuse link terminals which face each other.

A further object of this invention is to provide for holding the ends of a strain ,wire in the opposing ends of a pair of fuse link terminalsby deformation and for securing the ends of a. fusible .wire composed principally of tin thereto by heat and fusion.

. Still another important object of this invention is to positively hold one end of a sleeveof insulating material onto one terminal of a fuse link.

A still further object of this invention is to clamp one end of a sleeve of insulation to the knurled intermediate portion of a fuse link ter- 5 minal by crimping a retaining ring around the end of the sleeve.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

Accordingly, this invention is disclosed in the 10 embodiments hereof shownin theaccompanying drawing and it comprises features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention reference may be had to the following detailed description taken in connection with the accompanying drawing in which:

Figure 1 is a view, in side elevation, of one embodiment of this invention, the tubular insulating sleeve and the terminal cap being shown in section in order to more clearly disclose the details of construction;

Figure 2 is a view, in side elevation, of the tubular connector that is employed in the construction shown in- Figure 1 after the machining operations have been completed and before its ends have been deformed in the manner to be described hereinafter;

Figure 3 is a sectional view taken along the line 3-3 of Figure 1; Figure 4 is a sectional view taken along the line 4-4 of Figure 1;

Figure 5 is a view, similar to that shown in Figure 1, showing another embodiment of this invention;

Figure 6 is a sectional view taken along the line i-6 of Figure ,5;

Figure 7 is a sectional view taken along the line 1-1 of Figure 5; and

Figure 8 is a view showing certain parts of the fuse link illustrated in Figure 5 in disassembled relation. 7/

Referring now particularly to Figure 1 of the drawing, it will be observed that the reference character Ill designates, generally, afuse link that is intended for universal use in many of the expulsiori type cutouts that are being sold on the market today. The fuse link It] comprises fusible means I l which includes a fusible element l2, preferablyformed of silver, and a strain element nected.

i3, preferably formed of a nickel-chromium alloy for relieving the fusible element it of any tension stress that might otherwise be imposed thereon. The fusible and strain elements [12 and it are preferably in the term of wires with the former being formed in an open spiral around the latter. A flexible conductor i l, formed of a plurality of strands of line wire is arranged to be connected to the fusible means it in a manner to be hereinafter described. A cone terminal i pressed onto the flexible conductor id, as illus= tratecl, to permit attachment to a suitable minal of the cutout in which the fuse lint. ill is to be positioned.

the upper end oi the Knee link it] a terminal, generally at MS, is provided having upper end threaded indicated at ill for receiving a terminal cap 58. The loss link it) may be positioned in the bore oi the fuse housing the cap '18 engagement with the upper terminal thereof. For certain other types of fuse housing construction the terminal cap 58 may be removed and. the terminal it may be threaded into suit able connector. A flange i9 is provided interme diate the ends oi the terminal i6 by leaving this portion of the original steel: from which the ter minal is machined.

With a view to enclosing the 'lucdble means it and to provide an inherent expulsion action the fuse link to itself, a tubular sleeve oi iiisulatlon is provided. The tubular sleeve may be formed or fiber. The length oi the sleeve 22 is generally determined by the voltage of the circuit to which the fuse link ill is intended to he conin the drawing the sleeve 22 is shown relatively long for application to a high voltage circuit but it will be understood that a shorter length of sleeve may be employed without de= parting from the scope of this invention. The upper end of the sleeve 22 is crimped onto a knurled portion is of the terminal it. The ere treme upper end. is further crlmped into a circumferential groove 23 that is formed by a suitable machinlng operation between the flange i9 and the knurled portion 23.

For the purpose of providing for electrically connecting the fusible and strain elements iii and. it to the terminal it, its lower end it: is drilled axially at a. diameter that depends upon the size of these elements. The fusible and strain elements l2 and it are then inserted into the drilled hole and the opposite walls of it are deformed by flattening them as indicated at 26 on either side to cause the metal of the terminal to to come into intimate contact engagement with the ends of the fusible and strain elements it and S3. The upper end 2! of the strain element i3 is corrugated so that it is positively secured in the portion 25 of the terminal it when it is deformed thereon. in order to further insure that the metal of the terminal i5 is deformed into intimetc contact engagement with the upper ends oi the fusible and strain elements i2 and it, a suitable tool, such as a punch,

26 by forming the punch marks 28. The corruated end 2'! or the strain element i3 is embedded in the lower end 25 of the terminal it since the latter is usually formed oi brass or copper while the iormenas indicated. is formed oil a much harder material. The end of the fusible element it, being relatively soft, is flattened to conform to the adjacent inner surfaces.

Considerable difllculty has been encountered in the past in interconnecting the fusible means it is employed to further depress the metal on one oi the flattened portions and the flexible conductor i l, particularly in cer" tain current ratings and for certain types oi housing in which the available space is limited. it is desirable that this connection be formed in such manner that the internal diameter of the sleeve 22 may be as small as possible so that full advantage or the expulsion action may be taken on blowing or" the iusible means it to extinguish the are either in connection with the sleeve lit ltseli or the housing in which it may be installed. "it is also desirable to provide such a connection that the bore of the sleeve 22 will be substantially filled to obtaiw the maximum expulsion ac- Since the fuse link it is ordinarily subiected to considerable tension stress in order to obtainjrapid separation of the terminals between which the arc is drawn, this connection must be so formed as to resist this tension stress. 'Erom the standpoint oi heating under load conditions, the fuse link of the highest ampere rating designed for use in a particular cutout housing re quires the use of the largest flexible conductor it that can be inserted in the sleeve 22. A relatively massive terminal should be provided for the flexible conductor i l to serve as an arcing ter-- minal during short circuit interruption. The requirements then include the provision oi a relatively massive terminal, high contact pressure engagement with the strands of the conductor i and, at the same time, a minimum oi wall thickness to reduce the diameter or" the sleeve to a mlnlmiun. lit is undesirable to use soldered connections for the reason that the solder may be softened because of heat generamd from normal current flowing through the fuse link ill to such an extent that the tension applied may be sufli cient to pull the flexible conductor it away from. the fusible means ii.

According to the present invention this problem has been solved by the provision of the tubular connector, shown generally at 30., The maximum outside diameter ofthe tubular connector 3b is so chosen that it is slightly less than the internal diameter or" the sleeve 22. It is thereafter deformed, as will be presently described, in such manner that no change results in this maximum outside diameter. At the same time the bore of the sleeve 22 is substantially closed to obtain the desired expulsive effect.

The form and shape of the tubular connector 30 before it is deformed are illustrated in Figure 2. As there shown, the upper end portion 3| is somewhat reduced in section balance of the connector and it has an axially drilled hole 32 therein. The upper end 3| is beveled and the diameter of the drilled hole 32 depends upon the size of the fusible and strain elements l2 and I3. It will be understood that larger diameters of fusible and strain elements are employed for larger current ratings. After the lower ends of the fusible and strain elements it and I3 have been inserted in the hole 32 the opposite sides of the upper portion 3| of the connector 30 are deformed to cause the metal to come into intimate contact engagement with these lower ends. It will be observed that this construction and method of assembly are identical with the construction and method of assembly of the upper ends of the fusible and strain elements l2 and i3 into the lower portion 25 o! the terminal IS. The lower. end 34 of the strain element I3 is corrugated and the metal of the connector 30 is further forced into contact engagement with the lower ends of the Iusible and strain elements 12 and I3 by means of a tool such as compared to the as a punch which leaves indentations as indicated at 351 as previously described.

As illustrated, the lower end 36 of the tubular connector 30 is of sufficient diameter to substantially fill the bore of the sleeve 22. This end is drilled out to provide the longitudinal aperture 31 therein. The diameter of the aperture 31 is such as to readily permit the insertion therein of the upper end of the flexible conductor II.

In order to securely hold the tubular connector 30 to the upper end of the flexible conductor I 4 and to provide high contact pressure therebetween, the opposite sides of the lower end 36 or a substantial portion of its walls are longitudinally and transversely deformed and sprung to form longitudinal and transverse arched portions that extend inwardly as indicated at 38 in Figures 1 and 3 of the drawing. This deformingand springing operation is performed by placing the end 36 of the tubular connector 30 in a suitably shaped forming die and moving or springing the opposite walls inwardly by suitably shaped tools, the transverse dimensions of which in en gagement with these walls is somewhat less than the diameter of the aperture 31, to such an extent that they assume the positions shown in Figure 3 a where the transverse arched construction is clearly illustrated. The longitudinal edges 39 of the deformation 38 extend inwardly so that the portions 40 therebetween are braced radially to a substantial extent. The length and width of the deforming tools are so chosen that the resulting deformations 38 of the portion 36 are entirely within its confines with the upper and lower ends being substantially unaffected, with the crosssectional area midway between them being substantially reduced, and with no increase in maximum outsidedimension. These end portions retain their original shape and spacing and thus provide for substantially filling the sleeve 22 and yet leaving uniform clearance between the largest diameter of terminal 30- and the bore of the sleeve 22 to prevent sticking due to swelling of the latter with change in weather conditions.

While the transverse arched construction has been illustrated in Figure 3 of the drawing, it will be understood that a similar longitudinal arched construction is also present because of the shape of the ends of the deformations 38. In this manner the upper end of the flexible conductor I4 is secured within the end 31 of the tubular connector 30 and contact. engagement therebetween is provided under high pressure. The portions of the terminal stock along the edges 39 are permanently deformed and take a permanent set. In the flnal shape the outwardly acting resilient forces of the deformed strands of the conductor l4 are balanced by the inwardly acting resilient forces of the walls of the end 31. Since these walls are so curved that they are particularly adapted to resist these outwardly acting forces, a high contact pressure engagement remains therebetween after the deforming tools are removed. For purposes of illustration in the enlarged cross-sectional .view in Figure 3, the various strands of the flexible conductor l4 have been shown. As a matter of fact these several strands are compressed into a substantially solid section so that a saw cut or the like along the section line 3-3 would reveal substantially a plane surface.

The transverse and longitudinal inwardly arched construction may be more readily understood by comparing the sectional view as shown in Figure 3 with that shown in Figure 4 of the drawing. As shown in Figure 4 the upper portion of the cone terminal I 5 has been pressed into a rectangular shape onto the flexible conductor 14. Since the cone terminal is outside of the sleeve 22, its cross-sectionaldimensions are not limited to the extent that those dimensions of the terminal 30 inside the sleeve 22 are limited. As shown, a greater wall thickness may be employed and it is deformed onto the conductor I4 in the simplest possible manner, as by compressing it in a tool having a rectangular groove and a cooperating flat punch. The greater wall -thickness obviates the need of the inwardly arched construction used in the terminal 30 since the cone terminal I5 is deformed beyond its elastic limit to form a permanent set and thereby a rigid enclosure.

While the preferred method of assembling the tubular connector onto the upper end of the flexible conductor I4 is to employ the transverse and longitudinal arched construction, it will be understood that either of these constructions may be employed without the other by the use of suitably shaped forming tool s. However, in order to develop the full strength of the joint, it is preferable to use the combination of these two constructions.

From the foregoing it will be apparent that a fuse link construction has been provided in which the fusible means II is securely held in the terminal IS without the use of solder or other ma terial that might soften and loosen its hold because of heat developed while the fuse link I is conducting normal current. Likewise it will be observed that the fusible means I l and the flexible conductor I4 are positively interconnected without the use of solder or like material and at the same time high contact pressure is retained and the connection is inherently well adapted to withstand any tension stress that may ordinarily be applied thereto. Furthermore, the tension stress transmitting ability of the joint will not be changed despite the fact that it may be heated to an elevated temperature under normal operating conditions at which a material, such as solder, might be melted.

Another embodiment of the invention is illustrated in Figure of the drawing. As there shown the reference character 45 designates, generally, a fuse link that is also adapted for use as a universal fuse link in connection with various types of expulsion fuse housings. In this embodiment of the invention the fusible means, shown generally at 46, comprises a fusible element 4! that is formed preferably of tin and a strain element 48 that may be formed of a nickelchromium alloy, similar to the strain element l3 described hereinbefore.

The fuse link 45 may be connected into the circuit by a flexible conductor 49 that is similar to the conductor l4 and which is provided with a cone terminal 50 that is similar to the cone terminal IS. The lower'end 5| of the flexible conductor 49 may be dipped into solder in order to prevent the strands fraying.

At its upper end a terminal, shown generally at 52, is provided that is similar to the terminal l6. It is provided with a threaded portion 53 for receiving a threaded terminal cap 54. The flange 55 is provided intermediate the ends of the terminal 52 and it may be the diameter of the stock from which it is machined.

In this embodiment of the invention a sleeve 56 of insulation is provided and it may be composed of rolled paper. Tile upper end of the u receiving portion sleeve is onto a portion or the terminal 52 Since the sleeve [36 eom= posed. of paper, it desirable that some 3656i. tiorlal means provided for securiug the terminal and. for this purpose retaining ris 58 is provided. l tially the rig S is oi su diameter will readily at over the outside of the sleeve it may be crimpecl into position for holding the sleeve iu place showu i Figure 6 of the eirawium A flange [59, hey as shown, is prcvielerl below the lrrurleol por to preve t the paper sleeve from being pulleol off the terminal The lower port on "Si oi the terminal formed. ciifiererltli than the lower portion 25 the terminal it. As shown ill. of the drawing, the lower portion Cl is olrillecl out as lllolicateo'; at and then it is cieiormerl, as shown in Figure "l, to form a fusible element This cleiormiug operation serves two purposes. First, the upper corrugated eucl of the strain element 68 is embeclcied therein, as shown in Figure 7, so that it is se= curely held in position. Second, the fusible element receiving portion is formed for readily receiving the upper eucl of the fusible elementil. This may be secured therein as by solder which is indicated, at

It will be w'lderstoozi that the deformation of the lower portion 6i oi the terminal is s cient to cause the metal to come into intimate contact with the corrugated euoi of the strain element Gil. It is thus positively secured in position and held in place against any ordinary ten siori stresses that may be applied thereto. By providing the fusible element receiving portion in the lower portion 60 of the terminal [52 the assembly of the fusible element ll with it is facilitated, A minimum oi? solder is required and at the same time a maximum of the surface, as shown in Figure "l, is exposed;

thereto.

The fusible means it is secured to the flexible conductor by tubular connector that is shown generally at The upper end E8 of this connector is similar to the lower end portion 60 of? the terminal lice lower corrugated end. of the strain element til is secured therein in a similar manner as is also the lower end of the fusible element It will be observed that a cradle for receiving the fusible element ll is provided by deforming the and portions ti and of the terminals 52 and ill, respectively orlto the corrugated enols tit of the strain element By this means it is possible to accurately space these portions apart and to maintain. this spacing while sufiicient heat is applied to solcier the ends of the fusible element Win the semi-cylindrical sockets adapt co to receive them. Therefore, the heatemployeel to perform the soldering operation does not loosen the joints between the strain element and the terminals. Moreover, varying tensions that will ordinarily be applied during. assembly or in the field tending to separate the terminals tit anol ti do not, with this construction, cause a change in the spacing therebetweeu. Because of the accurate spacing thus provided. the free length of the fusible element, and hence its timecurrent characteristics, will always be the same for a given ampere rating.

In order to secure the tubular connector St to the upper end of the flexible conductor @9- its lower end portion 6!; is deformed longitudinally and transversely, as described hereinbefore with reference to the manner in which the lower enci 36 of tubular connector 80 is the poo eu oi the flexible conductor i l,

ce further changes may in tei all matter coat the go -g ciesci lieu showu iii the drawing iuterpreteo ill at Nive hot o i as our u:

l. in combination, iusible means, a flexible conductor, and connector lutereol, lecting said fusible means and flexible conductor auol secureol to the latter by having a substantial portion of the wall of the connector longitudipally coextensive with. the conductor arched in warclly onto the conductor.

2. a fuse, is couibiuatiou, fusible means ineluding strain iuslble elements, flexible conductor, auol a connector interconnecting said fusible means and salol iieiuble conductor, said. connector being securecl to said strain element by deformation thereon and to said flexible cozicluctor by having a substantial portion oi its well coextensivetherewith arched inwardly onto the same.

In a fuse, in combination, fusible means, a flexible conductor, and a tubular connector in terconnectirig saicl' fusible means and said iiexible conductor, said tubular connector having a substantial portion of its periphery enclosing said flexible coucluctor archeol inwardly.

4. In a fuse, in combination, fusible means incluolirig strain and fusible elements, a flexible conductor, and a tubular connector interconnecting said fusible means and said flexible condoctor, said tubular connector being deformed at one ehcl in such manner as to hold said strain element in engagement therewith and at the other end in such manner as to hold said flexible conductor therein by having a substantial portion or" its periphery enclosing the same arched inwardly.

5. in a fuse, in combination, fusible means ineluding strain and fusible elements, a flexible conductor, and a tubular connector interconnecting said fusible means and said flexible conrluctor, said tubular connector being deformed at one end onto said strain and fusible elements and at the other end; onto said flexible conductor by an inwardly arched deformation."

6. In a fuse, a relatively infuslble terminal, a fuse wire and, a strain wire each having one end extending into one end of said terminal, and a flexible conductor having one end. extending into the other end of said terminal, the metal of the terminal around the ends of the fuse and strain wires being permanently .(leformed thereon and around the end 01' the flexible conductor being permanently inwardly arched both to insure electrical contact engagement.

7. In a fuse link, in combination, a conductor. and a terminal having a tubular end portion for receiving said conductor, a substantial portion of the surface of said tubular end portion being archecl inwardly onto the end of said conductor therein for fixedly holding the some in position.

8. In a fuse, a tubular connector for connectl ou. at one'end to fusible means and arranged and adapted to receive a flexible conductor com prising a plurality of strands of wire at the other end, said other'end of said tubular connector being deiformecl in such manner as to secure said flexible conductor therein by having a. substantial portion of its periphery enclosing the same arched inwardly.

9. In a fuse, a tubular connector for connection at one end to fusible means and arranged and adapted to receive a. flexible conductor comprising a plurality of strands of wire at the other end, said other end of. said tubular connector being longitudinally arched inwardly to secure said flexible conductor therein.

10. In a fuse, a tubular connector for connection at one end to fusible means and arranged and adapted to receive a flexible conductor comprising a plurality of strands of wire at the other end, said other end of said tubular connector being transversely arched inwardly to secure said flexible conductor therein.

11. In a fuse, a tubular connector for connection at one end to fusible means and arranged and adapted to receive a flexible conductor comprising a plurality of strands of wire at the other end, said flexible conductor substantially filling said other end of said tubular connector, said other end of said tubular connector being longitudinally and transversely arched inwardly in such manner that said flexible conductor is secured therein.

12. The method of securing a terminal having a tubular end portion to a flexible conductor comprising a plurality of strands of wire which comprises inserting one end of the flexible conductor into the tubular end portion, and deforming the tubular end portion inwardly onto the flexible conductor in such manner as to provide longitudinally and transversely arched configurations therein. v

13. The method of securing a terminal having a tubular end portion to a flexible conductor comprising a plurality of strands of wire which comprises inserting one end of the flexible conductor into the tubular end portion, and exerting suflicient force on opposite sides of the tubular end portion to deform it inwardly onto the flexible conductor in such manner as to provide longitudinally and transversely arched configurations therein and to reduce the stranded conductor within the deformed portion to a substantially solid section.

14. In a fuse, in combination, a pair of terminals, a fusible element composed principally of tin interconnecting said terminals, and a strain element for relieving said fusible element of tension stress applied to said terminals, the ends of said strain element being corrugated and said terminals being deformed thereon and secured thereto solely by such deformation.

15. A cradle for receiving a. fusible element comprising, in combination, a pair of terminals disposed in predetermined spaced relation and having tubular end portions extending toward each other, and a strain element interconnecting said terminals with its ends disposed in said tubular end portions, said tubular end portions being deformed in such manner onto said ends of said strain element as to form substantially U-shaped fusible element receiving portions.

16. In a fuse, in combination, a pair of terminals having tubular end portions extending to ward each other, a strain element interconnecting said terminals with its ends disposed in said tubular end portions, said tubular end portions being deformed in such manner as to form sub stantially U-shaped fusible element receiving portions, and a fusible element also interconnecting said terminals with its ends disposed in said U-shaped fusible element receiving portions.

17. In a fuse, in combination, a pair of terminals having tubular end portions extending toward each other, a strain element for interconnecting said terminals with its ends disposed in said tubular end portions, said tubular end portions being deformed about said strain element in such manner as to embed the same therein and to form substantially U-shaped fusible element receiving portions, and a fusible element also interconnecting said terminals with its ends disposed in said U-shaped fusible element receiving portions.

18. In a fuse, in combination, a pair of terminals having tubular end portions extending toward each other, a strain wire for interconnecting said terminals with its ends disposed in said tubular end portions, said ends of. said strain wire being corrugated and said tubular end portions being deformed thereon in such manner as to embed them therein and to form substantially U-shaped fusible element receivingportions, and a fuse wire also interconnecting said terminals with its ends disposed in and soldered to said U- shaped fusible element receiving portions.

19. In a fuse, in combination, a tubular connector having one end longitudinally deformed to provide a substantially U-shaped fusible element receiving portion, a fusible element secured in said receiving portion, and a flexible conductor comprising a plurality of strands of wire having one end disposed in the other end of said connector, said other end of said connector being arched inwardly to secure said conductor therein.

20. In a fuse, in combination, a strain element, a tubular connector having one end longitudinally deformed onto one end of said strain element for securing it therein and to provide a substantially U-shaped fusible element receiving portion, a fusible element secured in said receiving portion, and a flexible conductor comprising a plurality of strands of wire having one end disposed in the other end of said connector, said other end of said connector being arched inwardly to secure said conductor therein.

21. In a fuse, in combination, a strain element, a flexible conducting element, and a terminal having oppositely extending tubular end portions for receiving the ends of said elements, a substantial portion of each of said tubular end portions being arched inwardly onto the element therein for flxedly holding the same in-position.

22. The method of securing a train element having at least one corrugated end portion and a fusible element to a terminal having a tubular end portion which comprises deforming the tubular end portion onto the corrugated end portion of the strain element and at the same time forming a U-shaped fusible element receiving portion therein, and securing one end of the fusible element in the U-shaped fusible element receiving portion. a

23. The method of securing a strain wire having a corrugated end portion to a terminal having a tubular end portion which comprises inserting the corrugated end of the strain wire into the tubular end portion, and deforming the tubular end portion onto the corrugated end portion to embed the same therein and at the same time form a U-shaped fusible wire receiving socket.

24. The method of securing a strain wire having a corrugated end portion and a fusible wire to a terminal having a tubular end portion which comprises inserting the corrugated end of the strain wire into the tubular end portion, deform ing the tubular end portion onto the corrugated "5 Q element in lit end portion toiorm a ll shaped fusible re ceiving portion and to clamp the end of the strain wire therein, placing one end of theiusible wire in the U-shaped fusible wire receiving portion and securing the end of the fusible wire in posi= tion by heat and iusion.

25. In a fuse link, in combination; terminal fitting having a terminal attaching portion at one end, a fusible element receiving portion the other end, a knurled portion intermediate said ends, and a flanged portion intermediate said knurled portion andsaid fusible element receiving portion; a fusible element secured to said ifusible element receiving portion, a sleeve of insulation surrounding said fusible element in spaced rela tion and at one end extending over said flanged and knurled portions, and a retaining ring crimped around said one end of said sleeve and holding it in position on said knurled portion.

26. In combination, a flexible stranded conduc tor, and a connector including a tubular section having relatively thin walls surrounding said con-= ductor, the end portions of said tubular section being of substantially the initial form thereof and portions of said walls intermediate said end portions beingarched inwardly in at least one direction with no part extending radially beyond the confines of said end portions.

27. In combination, a flexible stranded conductor and a connector including a relatively thin walled tubular conductor receiving section having end portions and an intermediate portion,v

said end portions remaining substantially unchanged and said intermediate portion being re duced in cross-section by deformation of a substantial part of its wall onto said conductor in such manner that the strands thereof are retained in compression by a portion of said wall being concave and circular and another portion being convex and arched in at least one direction.

28. The method of securing a terminal having a tubular end portion to a stranded conductor which comprises inserting one end of the conductor into the tubular end portion, deforming the tubular end portion inwardly intermediate its ends onto the stranded conductor in such manner as to provide inwardly arched configurations without increasing the radial dimension of any part of the tubular end portion.

29. In a fuse, in combination, a pair of ter== minals, a fusible element interconnecting said terminals and secured thereto by fusion, and a strain element also interconnecting said tor minals and securedthereto solely by deforma tion of said terminals for relieving said fusible element of tension stress between said terminals.

30. The method of securing a pair of terminals having tubular end portions to the ends of strain and fusible elements which comprises deforming the tubular end portions onto the ends of the strain element, and securing the ends of the fusible element to the terminals by iusion.

31. The method of securing a pair of terminals having tubular end portions tothe ends of strain and fusible element which comprises deforming the tubular end portions onto the ends of the strain element and at the same time forming aligned U-shaped fusible element receiving por-= tions therein, placing the ends of said fusible said aligned ill-shaped portions,- and securingthe ends of said fusible element in post-=- tion in said d shaped portions by heat and fusion.

2. The method of securing the tubular end portion of a metallic connector to comprising a plurality of strands of wire which comprises: inserting one end of the stranded con ductor into the tubular end portion, and deforming the tubular end portion inwardly onto the stranded conductor in such manner as to provide least one longitudinally and transversely arched configuration therein.

33. The method of securing the tubular end portion of a metallic connector to a conductor comprising a plurality of strands of wire which comprises: inserting one end of the stranded conductor into the tubular end portion, and exerting sufficient force on opposite sides oi the tubular end portion to deform it inwardly onto the stranded conductor in such manner as to provide at least one longitudinally and transversely arched configuration therein and to reduce the stranded conductor within the deformed portion to a substantially solid section.

The method of joining a pair of conductors in end-to-end relation at least one of which is made up of a plurality of strands of wire which comprises inserting the ends of the conductor into the tubular end portions of a deformable metallic connector, and exerting sufilcient force on opposite sides of the tubular end portions to deform them inwardly onto the conductors therein by providing at least one longitudinally and transversely arched configuration in each end portion and to reduce the stranded conductor within its tubular end portion to a substantially connecting said terminals for relieving said tin fusible element of tension stress between said terminals by withstanding a substantial portion of the same, said strain element being secured to at least one of said terminals by deformation of the same thereonto.

37. The method of securing a terminal having a tubular end portion to one of the ends of strain and fusible elements which comprises deforming the tubular end portion onto one end of the strain element, and securing one end of the fusible element to the terminal by fusion.

3%. The method of securing a terminal having a tubular end portion to one of the ends of strain and fusible elements which comprises deforming the tubular end portion onto one end of the strain element and at the same time forming a U-shaped fusible, element receiving portion therein, placing one end ofthe fusible element in said U-shaped portion, and securing the end of said fusible element in position in said U-shaped portion by heat and fusion.

HUGH A. SIGURD I. LINDELL.

conductor CERTIFICATE OF CORRECTION. Patent No. 2,l7h,767. I October 5, 1959.

\ HUGH A. TRIPLETT, ET AL;

' It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Page 5, Second column, line 52, c1'aim'22, for "train" read strain; page 6, first column, line 65; claim 51, for the word' "element" 'read' elements; and that the Said Letters Patent should be read withthis correction therein that the eame may conform to the record of the case in the Patent Office.

Signed and sealed this 31t day' of October, A. D. 1939.

Henry Arsdale, Acting Commissioner of Patents.

CERTIFICATE OF 001212501 1011. 4 Patent no. 2,17u,767. Octobexi 19 9.

HUGH A. 'I'RIPLETT, ET AI.

It is hereby certified that error appearein the printed specification of the above numbered patent requiring correcti oh as follows Page 5, sec,- ond coluin line 52, c1'aim'22, for "train" read strain; page 6, first col-- umn, line 65; claim 31, for the word' "element" read! elements; andqthat the eaid Le 'tters Petent should be read with this correction" therein that the same nia y conform to-the' recordof the cese in the Patent Office.

Signed and sealed this 31% day .of October, A. p. 1939.-

Heni'y Van Aisd ale, i) Acting Commissioner of Patents.- 

